Method for allocating a device address to a substation in a network as well as a substation and a main station for a network

Abstract

A method for allocating a device address in a network to a substation connected by a point-to-point connection includes transmitting an initialization message from a main station to a substation, which message contains a part of the device address, determining a set communication address of the substation, generating a complete device address based on a received part of the device address and based on the communication address, and transmitting a response mesasge from a device to the main station, which response message contains an address selected from the group consisting of the communication address, the device address, and both.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a main station and a substation in a network, e.g. in a field bus network, and in particular the reception of external data and for the transmission of device-internally prepared data via the network. The invention also relates to a method for transmitting data in a network. [0002] Data networks, for example a field bus network, usually have a main station and one or more substations that are connected to one another by means of point-to-point connections. The main station and the substation constitute a ring network in which the main station is connected via a unidirectional network connection to a data input of the first substation, a data output of the first substation is connected to a data input of a second substation, a data output of the second substation is connected to a data input of a third substation, etc. The data output of the last substation is connected to a data input of the main station. [0003] Alt...

AI Technical Summary

Benefits of technology

[0013] This assures that in an IP communication, i.e. in a random communication of each of the network stations via the data network, if the network station is in the process of transmitting an internal data packet, then the received external data packet will not be forwarded. During the transmission of the internal data packet with the prepared data, this prevents an overlapping of external and internal data packets, which would cause the data contained therein to become unreadable.

[0016] In particular, the present invention can provide a real-time capable data network based on the Ethernet standard—in particular also for data networks with repeaters that do not currently have a switching function in accordance with switched Ethernet (in this case, the present invention offers the advantage that the favorable, rapid repeaters can be used, but the overlapping of packets can be reliably prevented).

[0017] According to another embodiment form of the present invention, the control unit can control the switching device so that in the first operating mode, the transmission of the received external data packet via the data output with the aid of the repeater is blocked until the received external data packet has finished arriving. This has the advantage that after the first data transmission unit has transmitted the internal data packet, it does not add a part of a received external data packet, which a receiver would be unable to interpret due to its incompleteness. In other words, the received external data packet is not transmitted via the repeater to the data output until the arrival of this data packet at the data input has finished. Only then can the data input be coupled via the repeater to the data output so that subsequently received external data packets can be forwarded once again via the repeater.

[0018] According to another embodiment form of the present invention, the control unit functions cyclically, in a first operating mode during a first time interval and in a second operating mode during a second time interval. A second data preparation unit for transmitting prepared data is provided. The control unit is connected to the switching device in order, in the second operating mode, to connect the data output to the repeater and the second data preparation unit in alternating fashion so that a part of a particular external data packet received at the data input is transmitted by the repeater to the data output and the prepared data are inserted into the data packet at a chronologically defined position of the defined data packet associated with the network station. This makes it possible for the network station to be used in a data network that has two chronologically defined communication channels. An IP communication channel is provided in the operating mode in which an external data packet arriving at a data input is not forwarded if an internal data packet containing data prepared in the network device is currently being transmitted.

[0021] It is also possible for the transmission of the received external data packet to the data network after the end of the transmission of the prepared internal data packet to be blocked until the received external data packet has finished arriving. It is thus possible to prevent the forwarding into the data network of only a tail end of a received external data packet, which would under certain circumstances be incorrectly interpreted by a network station.

Problems solved by technology

Particularly in the IP communication channel, the problem arises that two overlapping data packets become unusable and thus hinder data communication on the data network.

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